Three more nations joined an international investigation team probing war crimes in Ukraine on Tuesday, and the prosecutor of the International Criminal Court said he plans to open an office in Kyiv amid calls for those responsible for atrocities committed since Russia's invasion to be brought to justice.

During a two-day coordination meeting in The Hague, Estonia, Latvia, and Slovakia signed an agreement to join Lithuania, Poland, and Ukraine in the Joint Investigation Team, which will assist Eurojust in coordinating the exchange of evidence of crimes.

Prosecutor of the World Criminal Court Karim Khan stated that the teamwork demonstrates the international community's dedication to the law.

"I believe it demonstrates that a common front of legality is absolutely essential, not only for Ukraine... but for the continuation of peace and security throughout the world," he stated.

The illegal invasion of Ukraine by Moscow has been internationally condemned as an act of aggression. Russian soldiers have been accused of murdering citizens in the Kyiv neighborhood of Bucha and of launching numerous airstrikes on civilian infrastructure, including hospitals and a theater in the besieged city of Mariupol, where hundreds of civilians were taking refuge. The Associated Press discovered proof indicating the bombing on March 16 killed approximately 600 persons inside and outside the building.

Since Russia's invasion on February 24, the Associated Press and the PBS series Frontline have confirmed 273 probable war crimes.

Ukrainian President Volodymyr Zelenskyy has referred to the slaughter of civilians as "genocide" and "war crimes." In contrast, U.S. President Joe Biden has referred to Russian President Vladimir Putin as "a war criminal" who should be tried.

The team that convened on Monday and Tuesday at Eurojust's offices in The Hague was formed in late March, a few weeks after the International Criminal Court started an investigation in Ukraine after dozens of the court's member states backed a probe. Khan has visited Ukraine, including Bucharest, and has the largest team of investigators ever sent by the international court to collect evidence in the country.

Khan now intends to create an office in Ukraine "within the coming weeks."

Iryna Venediktova, the general prosecutor of Ukraine, stated that her office has already initiated over 15,000 war-related criminal investigations and identified over 500 individuals, including Russian ministries, military commanders, and propagandists. She said that her office was prepared to move against approximately 80 of them.

In the first case related to the war, a Ukrainian court sentenced a captured Russian soldier to life in jail for the murder of a civilian last week. Tuesday, a Ukrainian court convicted two Russian soldiers of war crimes for shelling civilian buildings and sentenced them to 11 and a half years in prison each.

Russia vehemently claims that its troops have committed atrocities. The Defense Ministry stated earlier this month that "not a single civilian has been subjected to any form of military violence."

Analysts caution that meeting justice will be lengthy and complicated as investigators piece together forensic and other evidence to determine who ordered or knew about crimes but did nothing to prevent or punish them.

Not only at the meeting in The Hague is accountability being sought.

Poland, Germany, Lithuania, Latvia, Estonia, France, Slovakia, Sweden, Norway, and Switzerland launched their inquiries. In addition, there are mounting calls for establishing a special tribunal to try Russia for its aggression in Ukraine. The International Criminal Court cannot prosecute the crime of aggression because neither Russia nor Ukraine is a member.

Khan stated that the unified front of nations probing atrocities since the Russian invasion "hopefully can provide some measure of accountability for the crimes we are witnessing in Ukraine, which should not be tolerated any longer."